Re: [APML] NGC7000 Mexico Tricolor

["Richard Crisp" <rdcrisp@earthlink.net>]

----- Original Message -----
From: "Chuck Vaughn" <aa6g@aa6g.org>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Sunday, September 21, 2003 4:09 PM
Subject: Re: [APML] NGC7000 Mexico Tricolor


> John,
>
> Thanks. I found all obvious uneven development was due to moisture. We
> don't get much moisture up here with low temps running 70-80 F all
> summer. :-)  Yes, the OII line at 370nm contributes a lot of blue in
> some nebulas. It is interesting that it has so much OII and the Pelican
> right next door has practically none.
>
> Chuck <aa6g@aa6g.org>
>
>


Beautiful image. I had written Chuck privately but will share part with the
list.

On the [OII], I think if you have ionized oxygen species, you may get both
[OII] and [OIII] and the [OIII] is a great CCD filter because the wavelength
is in a sweet spot in terms of quantum efficiency in the sensors.

For those of you that know me from the SBIG and FLI and other CCD groups,
you know I have been mostly shooting emission line filters for the past few
months.

I like the way that I can enhance contrast using them and often reveal
otherwise latent structure.

I had shot this same basic region with Ha and [OIII] filters earlier in the
summer with a CCD camera. I had planned to do the same treatment to the
Pelican, right next door and found there was little [OIII] signal there,
just as Chuck reported relative to [OII]

Just for fun, I'm including a link to that Ha[OIII] image. I did not shoot
any [SII] that day, so just used the [OIII] for both my Green and Blue
channels. The top image has a bad gradient in it, but I sort of liked the
effect it gave the image: sort of reminds me of a landscape painting I once
saw from the early 1800s. I corrected (more or less) the gradient in the
second image.

http://www.rdcrisp.darkhorizons.org/ngc7000_north_america_nebula_page.htm

Sorry for posting a ccd image, but I think the Ha/OIII view of it may be
interesting to the group in the context of this thread.

Best regards
Richard


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